The present invention relates to a scroll-type compressor and more particularly to an improvement of sealing structure for securing end surfaces of housings of the compressor.
In general, the scroll-type compressor has a housing in which a fixed scroll member and a movable scroll member are provided. The fixed scroll member has a fixed scroll base plate and a fixed scroll volute portion that extends from the fixed scroll base plate. The movable scroll member has a movable scroll base plate and a movable scroll volute portion that extends from the movable scroll base plate Each volute portion is engaged with each other. The fixed scroll member and the movable scroll member cooperate to form a compression chamber as a compression region. As the movable scroll member orbits about an axis of the fixed scroll member, the compression chamber moves radially inward while its volume decreases.
As a typical prior art, Unexamined Japanese Patent Publication No. 8-338376 is known. In this constitution, as shown in FIG. 4, a fixed scroll member 111 is used as a center housing. Herein, a scroll-type compressor according to the above publication is turned to a scroll-type compressor as shown in FIG. 4 at an angle of 180 degrees for convenience. A front housing 112 and a rear housing 113 are respectively secured to front and rear sides of the center housing. The fixed scroll member 111 has a fixed scroll base plate 111a and a fixed scroll volute portion 111b that extends from the fixed scroll base plate 111a. A discharge port 111c for discharging compressed refrigerant is formed substantially at the center of the fixed scroll base plate 111a. The movable scroll member 118 has a movable scroll base plate 118a and a movable scroll volute portion 118b that extends from the movable scroll base plate 118a. The movable scroll volute portion 118b is placed to engage the fixed scroll volute portion 111b of the fixed scroll member 111. The fixed scroll member 111 and the movable scroll member 118 cooperate to form a plurality of compression chambers 120 as a compression region. The movable scroll member 118 is rotated by a drive shaft 114 connected to an external drive source. The movable scroll member 118 orbits about an axis of the fixed scroll member 111. Thus, the compression chambers are gradually compressed.
Still referring to FIG. 4, a ring-shaped fixed plate 126 is placed on an inner wall of the front housing 112. The front housing 112 is secured to the rear surface of the movable scroll base plate 118a. In the above compression mechanism, compression reactive force arises in accordance with compressing the refrigerant in the compression chambers 120. The compression reactive force in the direction of the axis acts on the fixed plate 126 through the movable scroll member 118.
In the above prior art, however, dimensional tolerance between height H1 of the fixed scroll volute portion 111b and height H2 of the movable scroll volute portion 118b is required to be adjusted. Therefore, the fixed plate 126 is alternatively fitted between the front housing 112 and the movable scroll member 118. Thus, a first distal end 111d of the fixed scroll volute portion 111b and a second distal end 118d of the movable scroll volute portion 118b are adjusted so that sealing performance is substantially equal at both ends. In this case, a plurality of the fixed plates 126 having different thickness is prepared. For example, each fixed plate 126 has a difference in thickness by 10 micrometer. When a compressor is assembled, the fittest fixed plate 126 is selected from a group of the fixed plates 126. That is, spare fixed plates 126 are required to be prepared and available for the trial and error. Therefore, the assembly requires a lot of man-hour.
In the above prior art, an O-ring seal 130 for creating a seal is placed between the fixed scroll member 111 and the front housing 112. To place the O-ring seal 130, a groove for the O-ring 130 is required to be formed. The groove is required to be accurately formed. Therefore, the machining cost becomes relatively high. Furthermore, such O-rings are required to be excellent in both sealing performance and durability. This also increases costs of the production.
The present invention addresses a scroll-type compressor having a sealing structure that has high sealing performance.
According to the present invention, a scroll-type compressor has a fixed scroll member, a movable scroll member, a rear housing, a front housing and a gasket seal. The fixed scroll member has a fixed scroll base plate and a fixed scroll volute portion. The movable scroll member has a movable scroll base plate and a movable scroll volute portion. The fixed scroll member and the movable scroll member cooperate to form a compression region. The movable scroll member orbits relative to the fixed scroll member to compress refrigerant in the compression region The movable scroll base plate forms a rear surface and a discharge hole. Pressure of the refrigerant discharged from the compression region is applied to the rear surface of the movable scroll base plate for enhancing a sealing effect in the compression region. The rear housing accommodates the fixed scroll member. The front housing is located adjacent to the rear housing for accommodating the movable scroll member. The gasket seal is located in contact with and between the front housing and the rear housing.